Production device for carbon fibers and production method therefor

ABSTRACT

An object of a production device and production method for carbon fibers of the present invention is to certainly obtain a connecting portion having a high process passing property with a simple mechanism so as to achieve a continuous operation and improve a firing process operability for achieving a low cost.  
     A pair of yarn gripping devices ( 12 ) for overlaying precursor fiber yarns to be connected one upon another and gripping the overlaid ends is provided, and a fluid processing unit for applying an entangling process by jetting a plurality of rows of fluid in along a yarn length direction is provided between the pair of yarn gripping devices ( 12 ). A plurality of discontinuous thread handling areas ( 11   b ) of the precursor fiber yarns in a fluid jet area of the fluid processing unit having fluid jet holes ( 11   a ) are disposed at predetermined, intervals (S).

TECHNICAL FIELD

[0001] The present invention relates to a production device for carbonfibers, comprising an end connecting device for connecting a trailingend of a preceding precursor fiber yarn and a leading end of a followingprecursor fiber yarn, and continuous production method for carbon fibersby connecting the ends of precursor fiber yarns using the productiondevice. More specifically, the invention relates to a production deviceand a production method for carbon fibers for applying a flame resistantprocess to precursor fiber yarns at the time of producing carbon fibers,and then applying a carbonizing process, being characterized in aconnecting device and a connecting method for yarns at the time ofcontinuously supplying precursor fiber yarns.

BACKGROUND ART

[0002] Carbon fibers have started to spread also for the industrialapplications such as architecture, engineering, and energy related usein addition to the conventional applications such as aircrafts andsports gears, with the demand therefor rapidly increased. In order tofurther accelerate the increase, realization of a carbon fiber of alower cost is desired. As a representative precursor fiber yarn forproducing a carbon fiber, there is an acrylic based fiber yarn, which iswidely used. According to the common carbon fiber production, carbonfibers are produced by obtaining flame resistant fibers by a flameresistant process of applying a heating process to acrylic based fiberyarns in an oxidizing atmosphere of 200 to 300° C., and subsequently acarbonizing process of applying a heating process in an inert atmosphereof 1,000° C. or higher. Since the carbon fibers thus obtained havevarious excellent physical properties, as mentioned above, they are usedwidely as reinforcing fibers for various kinds of fiber reinforcingcomposite materials, or the like in many fields.

[0003] In general, the acrylic based fiber yarns as the precursor fiberyarns for the carbon fiber production are supplied in a form wound up ona bobbin, or the like, or in a form folded and stacked in a box.Therefore, in order to achieve a low cost and improve the operability ofa firing process including a flame resistant process and a carbonizingprocess, a trailing end of an acrylic based fiber yarn of theaforementioned form needs to be connected with a leading end of anotheracrylic based yarn for providing a carbon fiber, because it is necessaryfor continuously transmitting the acrylic based fiber yarns and applyingthe firing process thereto so as to produce a carbon fiber.

[0004] As means for improving the operability in the firing process bycontinuously supplying the acrylic based yarn fibers in a productionprocess for carbon fibers with connecting the ends, for example,Japanese Patent Application Laid-Open No. 54-50624 discloses a methodfor applying to a connecting portion of acrylic based fiber yarns aflame resistant compound such as diester oil, silicone oil, halogenatedhydrocarbon, and a grease obtained from ore oil and a metal soap.Moreover, Japanese Patent Application Laid-Open No. 56-37315 discloses amethod for forming a connecting portion by preliminarily tying the endas a loop of an acrylic based fiber yarn after applying a thermalprocess, and entangling the same with the loop of another one.Furthermore, the Japanese Patent Application Publication No. 1-12850discloses a method for forming a connecting portion by entangling endsof acrylic based fiber yarns. Moreover, Japanese Patent ApplicationLaid-Open No. 4-214414 discloses a method for forming a connectingportion by entangling ends of acrylic based fiber yarns, andfurthermore, adhering to the connecting portion an oxidization reactioninhibiting agent such as boric acid, ammone sulfamate, sodium sulfite,and urea based compound, respectively.

[0005] However, the acrylic based fiber yarns having the connectingportions connected by the methods disclosed in the above publicationsare not compatible with the production condition for high speedproduction for carbon fibers having the excellent physical property.This is because the acrylic based fiber yarns having the connectingportions by the above methods cannot stably pass through a step ofproviding flame resistant fibers by a flame resistant process with highheating temperature and processing tension with respect to the acrylicbased fiber yarns, and a step of providing carbon fibers by acarbonizing process with a high processing tension. In particular, inthe case of connecting the precursor fibers with each other, burning andthread breakage are generated due to heat accumulation at the connectingportion.

[0006] Therefore, for passage of the flame resistant process and thecarbonizing process by the acrylic based fiber yarns having theconnecting portions by the connecting methods without a problem, thecondition of either the flame resistant process with the high heatingtemperature and processing tension or the carbonizing process with thehigh processing tension should be alleviated, and thus the carbon fiberscan hardly be produced by high speed production.

[0007] However, in the case where the acrylic based fiber yarns areconnected by merely tying the ends thereof with each other, drastic heataccumulation is caused at the connecting portion in the flame resistantprocess so that this causes the troubles such as the thread breakage inthe subsequent carbonizing process.

[0008] Furthermore, for example, Japanese Patent Application Laid-OpenNo. 10-226918 discloses a method for producing a carbon fiber byconnecting precursor fibers for carbon fiber production via a no heatgenerating connecting medium at a flame resistant temperature byentanglement at the single thread level, and a production devicetherefor. Gripping means for the precursor yarns and gripping means forthe connecting medium exist independently, and moreover, relax grippingportion for each entangling nozzle, that is, a plurality of relaxgripping means are provided. Furthermore, each of the relax grippingmeans comprises a mechanism to be moved independently with each otherfor providing a predetermined slacking amount to the precursor yarns,and thus it is an extremely complicated mechanism. Moreover, although itis mentioned that a plurality of nozzles are disposed at a predeterminedportion for the connecting process over a predetermined length so as toexecute bonding by fluid process at each portion, the number of arrangednozzles, or the arrangement interval are not specifically shown.

[0009] Thus, according to the prior arts, a connecting portion capableof realizing a certain process passing property with a device having asimple mechanism has not been obtained.

[0010] Therefore, an object of the present invention is to certainlyobtain a connecting portion having a high process passing property witha simple mechanism in a production device and a production method forcarbon fibers so as to achieve continuous operation and improve thefiring process operability for achieving a low cost.

DISCLOSURE OF THE INVENTION

[0011] The principal feature of the present invention for solving theproblem is a device for connecting precursor fiber yarns for carbonfiber production, being characterized by comprising a pair of yarngripping devices for overlaying and gripping precursor fiber yarns to beconnected, and a fluid processing unit disposed between the pair of yarngripping devices for applying an entangling process by jetting aplurality of rows of fluid with respect to a longitudinal direction tothe part with an overlaid part of the precursor fiber yarns, in whichthread handling areas of the precursor fiber yarns in the areacomprising the fluid processing unit having fluid jet holes are disposeddiscontinuously at predetermined intervals.

[0012] As the precursor fiber yarn for the carbon fiber production inthe present invention, in general, an acrylic based fiber yarn is used.The acrylic based fiber yarn is not particularly limited as long as itis an acrylic fiber containing an acrylonitrile as the main component,but an acrylic fiber comprising 95% by mass or more of acrylonitrile and5% by mass of a vinyl based monomer copolymerizable with acrylonitrileis preferable. Furthermore, it is preferable that the vinyl basedmonomer is one or more kinds of monomers selected from the group of themonomers having a flare resistant reaction promoting effect, consistingof acrylic acid, methacrylic acid, itaconic acid, or an alkaline metalsalt or an ammonium salt thereof, and acrylic amide.

[0013] In the carbon fiber production process in general, the precursorfiber yarns comprising the acrylic based fiber yarns, or the like areprocessed to be flame resistant fibers by a flame resistant processapplying heating process in an acidic atmosphere of 200 to 300° C., andthen providing carbon fibers by a carbonizing process applying heatingprocess in an inert atmosphere of 1,000° C. or higher.

[0014] The kind of the pair of gripping devices for overlaying andgripping the precursor fiber yarns in the present invention is notparticularly limited as long as they can overlay and grip the fiberyarns to be connected with each other, such as a nipping device forclamping and fixing yarns. The shape of the yarn gripping portion can bedetermined optionally according to the number of filaments and thenumber of deniers. Furthermore, it is further preferable to provide amechanism for slackening the part to be entangled and connected to bedescribed later by the operation for shortening the span, or the likeafter the pair of nipping mechanisms nip the acrylic fiber yarns fromthe viewpoint of executing the connection by the entangling processfurther effectively.

[0015] In the present invention, the fluid processing means disposedbetween the pair of gripping portions for applying an entangling processby simultaneously jetting a plurality of rows of fluid with respect to alongitudinal direction of the overlaid part of the fiber yarns is, asshown in FIG. 1, fluid processing means having fluid jet holes on threadhandling areas along the overlaid yarns. As shown in FIG. 2, the threadhandling areas are not formed continuously over the entire area of thefluid processing unit, but they are disposed with intervals per theplurality of rows of fluid jet holes provided in the longitudinaldirection.

[0016] Moreover, the fluid processing unit has fluid jet holes disposedin a plurality of rows with respect to the longitudinal direction of thethread handling areas along the yarns. The fluid can be supplied andjetted separately in respective fluid jet holes disposed in theplurality of rows, or it is also possible to supply and jet the fluidcollectively and simultaneously. In terms of the operability and thetime needed for the connection process, the latter is advantageous.

[0017] In the case where the thread handling areas are provided in thecontinuous structure without having the interval in each row of thefluid jet holes, wherein the fluid is supplied collectively, the fluidsjetted form the fluid jet holes disposed in the plurality of rows alongthe yarns interfere with each other in the thread handling areas.Particularly in the case of the fluid jetted in the vicinity of thecenter of the fluid processing means out of the fluid jet holes disposedin plural rows, due to a high pressure resistance, the jetting amountnecessary for the entanglement of the yarns cannot be obtained. As aresult, sufficient entanglement of the yarns cannot be obtained in thevicinity of the center. In the case where the thread handling areas areprovided continuously, even when the fluid is supplied individually foreach row of the fluid jet holes, since the fluid jetting lengths alongthe thread handling areas differ, turbulence of the yarns is generateddue to the turbulence of the jetted fluid flow, which is considered tobe derived from the thread handling area length to be described later sothat the respective entanglement cannot be even.

[0018] For the cross section of the thread handling area for overlayingand storing the fiber yarns to be connected with each other, variousshapes can be adopted according to the cross sectional shape of theyarns. However, as shown in FIG. 2, a flat rectangular shape isparticularly preferable. Although the size thereof differs depending onthe total fineness of the yarns to be connected, the shorter side of theflat rectangular cross sectional shape of the thread handling areas,which is in the yarn overlaying direction, that is, in the heightdirection is 1 to 5 mm, and preferably it is 2 to 4 mm. When the heightis small, that is, the thickness of the yarns is limited, the connectingportion tends to be firm so as to be the cause of the heat accumulationin the firing process. In contrast, when the size is large, although itdepends on the relationship with the longer side size, the entanglementtends to be insufficient due to thickening of the fiber bundle thicknessto be connected.

[0019] Concerning the longer side size, there is a preferable valuedependent on the total deniers of the two yarns to be connected. Thevalue is the ratio D/L of the total fineness D (dTex) and the longerside size L (mm) of the acrylic fiber yarn to be connected, and it ispreferable that the value is 2,000 to 5,000. When the D/L is 2,000 orless, the yarns are not spread in the entire thread handling area in awidth direction thereof, so that the two yarns are overlaid withdisplacement so as to generate twisting at the time of the entanglement,or in an extreme case, the two yarns are in the sate adjacent with eachother so as not to achieve the entanglement. Moreover, in contrast, whenthe value is 5,000 or more, that is, if the longer side size of the flatrectangular cross section is short, sufficient combination andentanglement cannot be generated due to the large thickness of the yarn.

[0020] As shown in FIG. 2, the fluid jet holes provided in a pluralityof rows along the longitudinal direction of the thread handling area areprovided with arranging a plurality of small holes in the longer sidedirection of the thread handling areas with the flat rectangular crosssectional shape. The bore of each fluid jet hole is preferably 0.3 to1.2 mm, and it is more preferably 0.5 to 1 mm. Furthermore, as to thearrangement of the fluid jet holes, it is preferable that they arearranged with an equal pitch in a range of 0.8 to 1.6 mm for obtainingan even entangled part. The length of each thread handling area to besectioned for each row of the fluid jet holes is preferably 10 to 40 mm.In particular, when the length is 40 mm or more, although the reasonthereof is not known, turbulence of the yarns, which is considered to bederived from the turbulence of the flow of the jetted fluid, occurs atboth ends of the thread handling areas so as to easily generate knotportions with each yarn forming a small bundle.

[0021] Furthermore, the interval between the respective thread handlingareas is preferably in a range of 1 mm to 100 mm, more preferably it is2.5 mm to 50 mm. By setting the interval in this range, although thereason is not known, the fluid jetted from the fluid jet holes in eachthread handling area is discharged from both ends of each threadhandling area via the thread handling areas such that it is clashedagainst the fluid discharged from the adjacent thread handling areas andbe discharged from the main body of the fluid processing means towardsideward thereof. In particular, when discharge is limited in the yarnoverlaying direction, that is, in the height direction by the commonbase plate or the upper-lid-side common plate as shown in FIG. 2, thefluid discharge to sideward becomes the main stream, and as a result,the fiber yarns are spread in the width direction of the thread handlingarea having the flat rectangular shape so as to enable the evenentanglement.

[0022] Furthermore, it is preferable that the fluid processing unit ofthe present invention has a structure dividable into half in thelongitudinal direction of the yarns to be overlaid in terms of theoperability at the time of disposing the fiber yarns. The fiber yarnsare overlaid in the state divided into half and disposed on the threadhandling areas, and then the fluid processing means main body is closed.The fixing method at the time of closing is not particularly limited,and thus appropriate means such as fastening by a screw, a clamp, or thelike can be selected. Furthermore, it is preferable that the fluidprocessing means divided into half along the thread handling areas hasthe thread handling areas integrated by a predetermined interval per rowunit of the fluid jet holes, or they are mounted on the common base interms of the convenience of the opening or closing operation.

[0023] In addition, according to the present invention, yarn cuttingmeans can be provided on the both end sides in the thread handling areadirection of the fluid processing unit and on the inner side of the yarngripping devices. In this case, it is preferable that the cuttingposition is provided with the distance from the connecting portion assmall as possible so that the generated end yarn is trimmed shortly interms of prevention of winding of the end yarns around the roll in thefollowing steps. Moreover, as to the end yarns generated at theconnecting portion of the yarns on the standby side bobbin, since a longend yarn can easily be the cause of winding to the roll in the followingsteps, it is preferable to provide the cutting means for trimming theend yarns as short as possible. From the reasons, the cutting positionby the cutting means can be set within 30 mm from the end of theoverlaid and entangled connecting portion.

[0024] The cutting means is not particularly limited as long as it is adevice to be supplied for ordinary cutting, comprising a cutting gear,or the like, capable of cutting the precursor fiber yarns, for example,scissors, a shirring device, a circular saw-like cutting device having arotary blade, a reciprocal clipper device having a fixed blade, anultrasonic cutter, or the like.

[0025] According to the invention, the aforementioned fluid processingunit divided into half can further be provided movably in the threadhandling area direction independently. By adopting the configuration, asshown in FIG. 3, at the time of entangling and connecting the fiberyarns, they can be cut by the cutting means preliminarily such that theend yarns can be short at the both ends of the fluid processing unit.Then, the fluid is jetted with the fluid processing means divided intohalf with respect to the yarn direction moved each on the yarn grippingdevice side such that the top ends of the cut end yarns are disposed onthe yarn gripping device side in the vicinity of the fluid jet hole,thereby mixing the end yarns into the entangled portion.

[0026] At the time, although it depends on the pressure of the suppliedfluid, the fineness of the yarns to be connected, or the like, byjetting the fluid after providing the distance from the fluid jet holesto the end face of the cut yarns within 10 mm, more preferably 5 mm, theend yarns can be mixed into the entangled portion. As a result, windingof the yarns to the roll derived form the end yarns in the carbon fiberproduction process, fiber mixture with the adjacent precursor yarns, andfurthermore, running disturbance by groove skipping by the groove roll,or the like derived from the fiber mixture can be avoided.

[0027] The leading end of the precursor fiber yarn newly supplied in thecarbon fiber production process and the trailing end of the precursorfiber yarn supplied preliminarily to the flame resistant process or thecarbonizing process are connected using the connecting device. At thetime of connecting the ends of the precursor fiber yarns by theconnecting device, since the continuous process is executed in the flameresistant process or the carbonizing process while stopping running ofthe running precursor fiber yarns by the gripping device of theconnecting device, the preceding precursor fiber yarn continues to run.

[0028] Therefore, according to the carbon fiber producing device of thepresent invention, it is preferable that a temporary storage unit fortemporarily storing a precursor fiber yarn being transported is providedbetween the connecting device for the precursor fiber yarn and the flameresistant process or the carbonizing process on the downstream side. Thetemporary storage unit comprises, for example, a movable roll mechanism.As the movable roll mechanism, there are a dancer roll system of runninga precursor fiber yarn placed on a roll surface on the opposite side ofa roll member forcing direction forced in one direction by a spring, orthe like along the running path of the precursor fiber yarn for apendulum-like operation, a system of running a precursor fiber yarnplaced on a roll surface on the loaded side of a running block movablefreely in the up and down direction with a certain load for elevatingthe running block-like roll member in the up and down direction, and thelike, and any one can be selected optionally from the systems.

[0029] The precursor fiber yarn to be temporarily stopped at theconnecting portion of the precursor fiber yarns during the operation ofthe gripping devices. On the other hand, they are supplied continuouslyto the flame resistant process or the carbonizing process so as to besupplied continuously and smoothly to each process while maintaining thetension substantially constantly by the movable roll mechanism of thetemporary storage unit. When the gripping devices are not operated, withthe precursor fiber yarns of the necessary and sufficient supply lengthat the time of operating the gripping devices ensured, they are suppliedcontinuously to the flame resistant process or the carbonizing processwhile temporarily storing the precursor fiber yarns of a certain amountby the forcing power or the load of the movable roll mechanism of thetemporary storage unit.

[0030] Furthermore, according to the invention, it is also possible toprovide a detector for detecting the trailing end of the precursor fiberyarn in the running path of the precursor fiber yarn on the yarnupstream side of the connecting device. Although the kind of thedetector for detecting the trailing end of the yarn is not limited atall, it is preferable to use a photoelectric detector that is notcontacted with the yarn. By detecting passage of the trailing end of therunning precursor fiber yarn by the detector, the pressured fluid issupplied to the fluid processing unit by operating, for example, a valvefor supplying a pressured fluid provided in the yarn connecting deviceso as to automatically execute the operation for connecting the yarnends with each other.

[0031] According to the invention, the fiber yarns can be producedcontinuously by using the connecting device for connecting the trailingend of the preceding precursor fiber yarn for producing the carbon fiberand the leading end of the following precursor fiber yarn. That is, theentangling process is applied by first overlaying the ends of theprecursor fiber yarns to be connected with each other, gripping the bothends of the overlaid part of the precursor fiber yarns by the yarngripping means, and jetting a plurality of rows of fluid to the overlaidpart between the yarn gripping devices in the longitudinal direction bythe fluid processing means.

[0032] It is preferable that at least one of the precursor fiber yarnsto be connected is provided preliminarily as a flame resistant yarn orthe connecting end is processed to be flame resistant before connectingthe trailing end and the leading end of the precursor fiber yarns.Furthermore, it is also possible to connect the trailing end and theleading end of the precursor fiber yarns via a flame resistant fiber.Also in this case, a pair of the gripping means on the both ends of theconnecting portion of the precursor fiber yarns is sufficient. The flameresistant process for the fiber yarn ends is not particularly limited,and thus it can be carried out, for example, by executing a heatingprocess at 200 to 300° C. in the air, ozone, or another oxidizedatmosphere. As the device for executing the heating process, a hot aircirculating furnace, a drier using an electric heater, or the like canbe used.

[0033] In the case of an acrylic based fiber yarn provided in a formwound around on a bobbin by a winder, the flame resistant process of thefinal end can be executed easily. That is, the final end can beprocessed with the above-described hot air circulating furnace, or thelike after finishing the winding-up operation. On the other hand, forthe flame resistant process to the winding starting end, the windingstarting end is wound around under the fiber yarn to be wound up by thewinder. That is, the fiber yarn is wound up while being overlaid on thewinding starting yarn end.

[0034] Therefore, even after finishing the winding-up operation for apredetermined amount, the inability of taking up the winding startingend from the bobbin should be avoided. Therefor, for example, at thetime of starting winding the fiber yarn, the yarn leading end of alength sufficient for the heating process by the hot air circulatingfurnace, or the like later is wound up at a position displaced form theyarn path to be wound up for forming the bobbin for winding up thefollowing yarn and forming a predetermined bobbin. Moreover, in the casewhere the trailing end of the preceding precursor fiber yarn and theleading end of the following precursor fiber yarn are to be connectedvia a flame resistant fiber at the time of the connecting operation, thefiber yarn after passing through the flame resistant process can be usedas the flame resistant fiber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035]FIG. 1 is a cross-sectional view showing a schematic configurationexample of a representative yarn connecting device to be applied to thepresent invention.

[0036]FIG. 2 is a configuration explanatory view showing an embodimentof a fluid jetting nozzle of the yarn connecting device.

[0037]FIG. 3 is an explanatory view for a yarn connecting procedureaccording to another embodiment of the yarn connecting device.

[0038]FIG. 4 is a production process explanatory view for a carbon fiberby the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0039] Hereinafter, an example for producing a carbon fiber continuouslywill be explained specifically mainly about the process passing propertyby employing the connecting device for yarns and the connecting methodconstituting the characteristic part the invention using an acrylicbased fiber yarn as the precursor fiber yarn for producing a carbonfiber. The process passing ratio presented in the following examples andcomparative example is the number of connecting portions without cuttingin each process for carbon fibers produced by providing a flameresistant process and a carbonizing process to acrylic based fiber yarnshaving connecting portions represented by the percentage (%) withrespect to the number of all the connecting portions of the yarns to betested. Moreover, the process tension (mN/Tex) is a numerical value ofthe tension of the acrylic fiber yarns in the flame resistant processand the carbonizing process at the time of producing the carbon fibersusing the acrylic based fiber yarns having the connecting portionsconverted per unit fineness.

[0040] As shown in FIG. 4, according to the carbon fiber production,precursor fiber yarns are taken out from bobbins 2 on a creel 1 so as tobe arranged in the horizontal direction by a comb tooth-like guide 3,supplied to a flame resistant process 6 and a carbonizing process 7 viafirst and second feed rollers 4, 5 for having each process, and aretaken up continuously by a winder as the carbon fiber as a final fiber.In the examples hereafter, a yarn gripping device 10 and a runningblock-like movable roll 8 constituting a temporary storage unit for ayarn, which are characteristic parts of the present invention, areprovided between the first feed roller 4 and the second feed roller 5.

[0041] The movable roll 8 for balancing while applying a certain tensionto the precursor fiber yarn under a certain load at the time when theyarn connecting device 10 is in a non-operation state, is disposed belowan ordinary yarn transporting path. Now, when the yarn connecting device10 is in an operation state, the fist feed roller 4 is stopped so as tostop the supply of the precursor fiber yarn from the creel 1. On theother hand, since the supply of the precursor fiber yarn to the flameresistant process 6 and the carbonizing process 7 is continued duringthat time, the movable roll 8 is lifted upward by the precursor fiberyarn so that the precursor fiber yarn is supplied smoothly to the flameresistant process 6 and the carbonizing process 7 under a predeterminedtension.

EXAMPLE 1

[0042] By applying a flame resistant process to an end of an acrylicbased fiber yarn of a 1.2 dTex/filament single yarn fineness and a12,000 filament number in a furnace with hot air of 240° C. circulatingunder a 5 mN/tex tension for 70 minutes, an acrylic based fiber yarn Ahaving a 1.36 g/cm³ density with the flame resistant end, and anotheracrylic based fiber yarn B were prepared.

[0043] For the flame resistant end of the acrylic based fiber yarn A andthe end of the acrylic based fiber yarn B, with applying the jettingnozzle 11 as fluid jetting means shown in FIG. 2 to the yarn connectingdevice 10 shown in FIG. 1, the both ends of the fiber yarns A and B wereentangled and connected using the air as the jetting fluid with thefiber yarn ends overlaid. In this example, the installation distance Sbetween a pair of yarn gripping devices 12, 12 in the yarn connectingdevice 10 shown in FIG. 1 was 300 mm. A plurality of jetting nozzles 11,11, . . . have the structure shown in FIG. 2. The nozzle thread handlingarea length L per each air jetting hole 11 a as a fluid jet hole was 20mm. The distance S1 between the adjacent nozzles 11, 11, . . . was 5 mm,and they were arranged by 10 pieces.

[0044] Each thread handling area 11 b with a rectangular cross-sectionalshape of 8 mm×2.5 mm has air supply openings 11 c formed on the upperand lower parts of each thread handling area 11 b along the longer sidedirection of the rectangular cross-section such that each air supplyopening 11 c communicates with the air jetting hole 11 a. The airjetting holes 11 a were formed each in 10 portions vertically in eachthread handling area 11 b. The diameter of the air jetting hole 11 a is0.5 mm. Furthermore, according to this example, as shown in FIG. 3(a), amain body 13 of a fluid processing unit has a structure dividable intohalf. In each divided member 13 a, 13 b, the jetting nozzles 11, 11, . .. are arranged each in 5 rows such that the upper and lower surfaces ofthe jetting nozzles 11, 11, . . . are fixed and integrated with thecommon plate 14.

[0045] In the thread handling area 11 b of the fluid processing unithaving the configuration, the flame resistant end of the acrylic basedfiber yarn A and the end of the acrylic based fiber yarn B without theflame resistant process were overlaid and stored so that the both endsof the overlaid part were gripped by the gripping devices 12 withoutslacking thereof in the sate with the yarns overlaid, and then thedivided members 13 a, 13 b of the fluid processing means were closed.Thereafter, by shortening the gripping distance of the yarn grippingdevices 12, 12 by 7.5 mm, slack was applied to the yarns. In this state,by supplying the entangling air by a 2.5 kg/cm² pressure for 3 seconds,the flame resistant end of the yarn A and the end of the yarn B withoutthe flame resistant process were entangled and connected, and theexcessive end yarns were cut off with the scissors so as to have 20 mmremain.

[0046] The acrylic fiber yarn having the connecting portion was providedfor the flame resistant process for 30 minutes in a flame resistantfurnace with the hot air of 230 to 270° C. circulating while limitingcontraction of the acrylic fiber yarn by a 14 mN/Tex process tension,and then for the carbonizing process for 2 minutes in a carbonizingfurnace containing a nitrogen atmosphere having a 300 to 1,300° C.temperature distribution while limiting contraction of the acrylic fiberyarn by a 7 mN/Tex process tension so as to produce a carbon fiber.

[0047] The process passing ratios of the yarn connecting portion in theflame resistant process and the carbonizing process in the carbon fiberproduction process at the time are as shown in Table 1.

EXAMPLE 2

[0048] By applying a flame resistant process to an end of an acrylicbased fiber yarn of a 1.2 dTex/filament single yarn fineness, and a24,000 filament number in a furnace with hot air of 240° C. circulatingunder a 5 mN/tex tension for 70 minutes, an acrylic based fiber yarn Chaving a 1.36 g/cm³ density with the flame resistant end, and anotheracrylic based fiber yarn D without applying a special flame resistantprocess to the end were prepared.

[0049] The flame resistant end of the acrylic based fiber yarn C and theend of the acrylic based fiber yarn D without the flame resistantprocess were entangled and connected by jetting the air with the jettingnozzle 11 shown in FIG. 2 in the yarn connecting device 10 shown inFIG. 1. In this example, the distance S between the yarn grippingdevices 10 was 300 mm. The jetting nozzles 11 had the structure shown inFIG. 2. The nozzle thread handling area length L per each air jettinghole 11 a was 20 mm. The main bodies 13 were arranged by a 5 mm distanceof the adjacent jetting nozzles 11 in 10 rows.

[0050] The thread handling areas 11 b had a rectangular cross-sectionalshape of 16 mm×2.5 mm. The air supply openings 11 c were formed on theupper and lower parts of the thread handling areas 11 b. The air jettingholes 11 a were formed each in 20 portions vertically in each threadhandling area 11 b with a 0.5 mm diameter. The main body 13 of the fluidprocessing unit has a structure dividable into half. The upper and lowersurfaces of the jetting nozzles 11, 11, . . . arranged each in 10 rowsper each divided member (not shown) are fixed and integrated with thecommon plate 14.

[0051] In the thread handling area 11 b of the fluid processing unithaving the configuration, the flame resistant end of the acrylic basedfiber yarn C and the end of the acrylic based fiber yarn D without theflame resistant process were overlaid and stored so that the overlaidparts of the precursor fiber yarn and the flame resistant yarn part weregripped by the gripping devices 12 without slacking thereof in the statewith the yarns overlaid, and then the divided fluid processing unit wasclosed. Thereafter, by shortening the gripping distance of the yarngripping devices 12 by 7.5 mm, slack was applied to the yarns.

[0052] In this state, by supplying the entangling air by a 2.5 kg/cm²pressure for 3 seconds, the flame resistant end of the yarn C and theend of the acrylic based fiber yarn D without the flame resistantprocess were entangled and connected, and the excessive end yarns werecut off and eliminated with the scissors so as to have 20 mm remain. Theacrylic fiber yarn having the bonding part was provided for the flameresistant process for 60 minutes in a flame resistant furnace with thehot air of 230 to 270° C. circulating while limiting contraction of theacrylic fiber yarn by a 14 mN/Tex process tension, and then for thecarbonizing process for 2 minutes in a carbonizing furnace containing anitrogen atmosphere having a 300 to 1,300° C. temperature distributionwhile limiting contraction of the acrylic fiber yarn by a 7 mN/Texprocess tension so as to produce a carbon fiber.

[0053] The process passing ratios of the yarn bonding part in the flameresistant process and the carbonizing process in the carbon fiberproduction process at the time are as shown in Table 1.

EXAMPLE 3

[0054] By applying a flame resistant process to an end of an acrylicbased fiber yarn of a 1.2 dTex/filament single yarn fineness, and a48,000 filament number in a furnace with hot air of 240° C. circulatingunder a 5 mN/tex tension for 70 minutes, an acrylic based fiber yarn Ehaving a 1.36 g/cm³ density with the flame resistant end, and anotheracrylic based fiber yarn F without applying a special flame resistantprocess were prepared.

[0055] The flame resistant end of the acrylic based fiber yarn E and theend without the flame resistant process of the acrylic based fiber yarnF were entangled and connected by entanglement by jetting the air usingthe jetting nozzle 11 shown in FIG. 2 in the yarn connecting device 10shown in FIG. 1. In this example, the distance S between the yarngripping devices 12 was 300 mm. The jetting nozzles 11 had the structureshown in FIG. 2. The nozzle thread handling area length L per each airjetting hole 11 a was 20 mm. The adjacent nozzles were arranged by a 5mm distance in 10 rows.

[0056] The thread handling areas 11 b had a rectangular cross-sectionalshape of 32 mm×2.5 mm. The air supply openings 11 c were formed on theupper and lower parts of the thread handling areas 11 b. The air jettingholes 11 a communicating with the air supply openings 11 c were formedeach in 40 portions vertically in each thread handling area 11 b with a0.5 mm diameter. The main body 13 of the fluid processing unit has astructure dividable into half. To the divided members (not shown), thejetting nozzles having the interval and arranged in 10 rows were fixedwith the common plate as in the example.

[0057] In the thread handling area 11 b of the fluid processing unithaving the configuration, the flame resistant end of the acrylic basedfiber yarn E and the end of the acrylic based fiber yarn F without theflame resistant process were overlaid and stored so that the both endsof the overlaid parts of the acrylic based fiber yarn E and the acrylicbased fiber yarn F were gripped by the gripping devices 12 withoutslacking thereof in the state with the yarns overlaid, and then thedivided members were closed. Thereafter, by shortening the grippingdistance of the yarn gripping devices by 7.5 mm, slack was applied tothe yarns. In this state, by supplying the entangling air by a 2.5kg/cm² pressure for 3 seconds, the flame resistant end of the yarn E andthe acrylic based fiber yarn end of the yarn F were entangled andconnected, and the excessive end yarns were cut off and eliminated withthe scissors so as to have 20 mm remain.

[0058] The acrylic fiber yarn having the bonding part was provided forthe flame resistant process for 60 minutes in a flame resistant furnacewith the hot air of 230 to 270° C. circulating while limitingcontraction of the acrylic fiber yarn by a 14 mN/Tex process tension,and then for the carbonizing process for 2 minutes in a carbonizingfurnace containing a nitrogen atmosphere having a 300 to 1,300° C.temperature distribution while limiting contraction of the acrylic fiberyarn by a 7 mN/Tex process tension so as to produce a carbon fiber.

[0059] The process passing ratios of the yarn bonding part in the flameresistant process and the carbonizing process in the carbon fiberproduction process at the time are as shown in Table 1.

EXAMPLE 4

[0060] As in Example 1, by applying a flame resistant process to an endof an acrylic based fiber yarn of a 1.2 dTex/filament single yarnfineness, and a 12,000 filament number in a furnace with hot air of 240°C. circulating under a 5 mN/tex tension for 70 minutes, an acrylic basedfiber yarn G having a 1.36 g/cm³ density with the flame resistant end,and another acrylic based fiber yarn H without applying a flameresistant process were prepared.

[0061] The flame resistant end of the acrylic based fiber yarn G and theend of the acrylic based fiber yarn H without the flame resistantprocess were entangled and connected by entanglement by the air usingthe yarn connecting device 10 shown in FIG. 3. In this example,according to the yarn connective device 10 shown in FIG. 3, the grippingdistance S of the yarn gripping devices 12 was 300 mm. The jettingnozzles 11 had the structure shown in FIG. 2. The nozzle thread handlingarea length per each jetting hole 11 a of the jetting nozzle 11 was 20mm. The adjacent jetting nozzles were arranged by a 5 mm arrangementinterval, and two sets of the fluid processing units each having thesame by 5 rows were used.

[0062] Each fluid processing unit has thread handling areas 11 b with arectangular cross-sectional shape of 8 mm×2.5 mm. The air supplyopenings 11 c were formed on the upper and lower parts of the threadhandling areas 11 b. The air jetting holes 11 a communicating with theair supply openings 11 c were formed each in 10 portions vertically ineach thread handling area 11 b with a 0.5 mm diameter. The main body 13of the fluid processing unit has a structure dividable into half. A setof the jetting nozzle group arranged each in 5 rows is fixed with thecommon plate.

[0063] In the thread handling area 11 b of the main body 13 having theconfiguration, the flame resistant end of the acrylic based fiber yarn Gand the end of the acrylic based fiber yarn H without the flameresistant process were overlaid and stored so that the both ends of theoverlaid parts of the acrylic based fiber yarns G and H were gripped bythe gripping devices 12 without slacking thereof in the state with theends of the yarns G, H overlaid, and then the main bodies 13, 13 of thetwo sets of the fluid processing units were closed along the threadhandling areas 11 b.

[0064] Thereafter, the end yarn of the flame resistant leading end ofthe acrylic based fiber yarn G and the trailing end of the acrylic basedyarn fiber G projecting from the both ends on the outer side of the pairof yarn gripping devices 12 were cut by the ultrasonic cutter SUW-30CMHproduced by Suzuki Corp. As to the blade type used at the time, the typenumber H4 made of a steel material of a high speed tool steel having a0.5 mm blade thickness, with a stainless steel jig having a 30 degreeangle with respect to the blade tip with a 0.3 mm distance from the bothsurfaces of the blade for closely contacting the yarn with the blade,was used. By inserting the cutter so as to dispose the yarn between theblade and the jig inclined surface, the end yarn was cut.

[0065] After cutting the end yarn accordingly, as shown in FIG. 3(b),the main body 13 of the fluid processing unit with each 5 rows providedas a set was moved each toward the yarn gripping devices 12 by 25 mm soas to set the distance between the end yarn top end and the air jettinghole 11 a adjacent to the top end to 5 mm. After the operation, byshortening the gripping distance of the yarn gripping devices by 7.5 mm,slack was applied to the yarns. In this state, by supplying theentangling air by a 2.5 kg/cm² pressure for 3 seconds, the flameresistant end of the yarn G and the acrylic based fiber yarn end of theyarn H without the flame resistant process were entangled and connected.The obtained bonding part had a state with the end yarn mixed.

[0066] The acrylic fiber yarn having the bonding part was provided forthe flame resistant process for 30 minutes in a flame resistant furnacewith the hot air of 230 to 270° C. circulating while limitingcontraction of the acrylic fiber yarn by a 14 mN/Tex process tension,and then for the carbonizing process for 2 minutes in a carbonizingfurnace containing a nitrogen atmosphere having a 300 to 1,300° C.temperature distribution while limiting contraction of the acrylic fiberyarn by a 7 mN/Tex process tension so as to produce a carbon fiber.

[0067] The process passing ratios of the yarn bonding part in the flameresistant process and the carbonizing process in the carbon fiberproduction process at the time are as shown in Table 1.

EXAMPLE 5

[0068] By applying a flame resistant process to an end of an acrylicbased fiber yarn of a 1.2 dTex/filament single yarn fineness, and a48,000 filament number in a furnace with hot air of 240° C. circulatingunder a 5 mN/tex tension for 70 minutes, an acrylic based fiber yarn Ihaving a 1.36 g/cm³ density with the flame resistant end, and anotheracrylic based fiber yarn J with the end processed in the same mannerwere prepared.

[0069] The flame resistant end of the acrylic based fiber yarn I and theflame resistant end of the acrylic based fiber yarn J were entangled andconnected by entanglement by jetting the air using the jetting nozzle 11shown in FIG. 2 in the yarn connecting device 10 shown in FIG. 1. Inthis example, the distance S between the yarn gripping devices 12 was300 mm. The jetting nozzles 11 having the structure shown in FIG. 2 wereused. The nozzle thread handling area length L per each air jetting hole11 a was 20 mm. The adjacent nozzles were arranged by a 5 mm distance in10 rows.

[0070] The thread handling areas 11 b had a rectangular cross-sectionalshape of 32 mm×2.5 mm. The air supply openings 11 c were formed on theupper and lower parts of the thread handling areas 11 b. The air jettingholes 11 a having a 0.5 mm hole diameter, communicating with the airsupply openings 11 c were formed each in 40 portions vertically in eachthread handling area 11 b. The main body 13 of the fluid processing unithad a structure dividable into half. The air jetting nozzles 11 arrangedin 10 rows were fixed with the common plate 14.

[0071] In the thread handling area 11 b of the fluid processing unitmain body 13, the flame resistant end of the acrylic based fiber yarn Iand the flame resistant end of the acrylic based fiber yarn J wereoverlaid and stored so that the both ends of the overlaid parts of theacrylic based fiber yarn I and the acrylic based fiber yarn J weregripped by the gripping devices 12 without slacking thereof in the statewith the yarns overlaid, and then the main body 13 of the fluidprocessing unit divided and separated was closed. Thereafter, byshortening the gripping distance of the yarn gripping devices by 7.5 mm,slack was applied to the yarns. In this state, by supplying theentangling air by a 2.5 kg/cm² pressure for 3 seconds, the flameresistant end of the yarn E and the end of the acrylic based fiber yarnJ of the yarn F were entangled and connected, and the excessive endyarns were cut off and eliminated with the scissors so as to have 20 mmremain.

[0072] The acrylic fiber yarn having the bonding part was provided forthe flame resistant process for 60 minutes in a flame resistant furnacewith the hot air of 230 to 270° C. circulating while limitingcontraction of the acrylic fiber yarn by a 14 mN/Tex process tension,and then for the carbonizing process for 2 minutes in a carbonizingfurnace containing a nitrogen atmosphere having a 300 to 1,300° C.temperature distribution while limiting contraction of the acrylic fiberyarn by a 7 mN/Tex process tension so as to produce a carbon fiber.

[0073] The process passing ratios of the yarn bonding part in the flameresistant process and the carbonizing process in the carbon fiberproduction process at the time are as shown in Table 1.

COMPARATIVE EXAMPLE 1

[0074] In the same manner as in Example 1 using the jetting nozzlehaving the same structure as in Example 1 except that the air jettingnozzles used for the entanglement and the connection had the structurewith the thread handling areas provided continuously, an acrylic basedfiber yarn K having the flame resistant end, and another acrylic basedfiber yarn L without the flame resistant process were connected byentangling by supplying the air of the same pressure as in Example 1 for3 seconds. The acrylic fiber yarn having the bonding part was suppliedto the carbon fiber production process with the same conditions as inExample 1. The process passing ratios of the connecting portion in theflame resistant process and the carbonizing process in the carbon fiberproduction process at the time are as shown in Table 1. The suppliedbonding parts were cut in the flame resistant process so that theycannot be supplied to the subsequent processes. According to the bondingparts obtained at the time, the entanglement was not even for eachjetting hole. In particular, the entanglement was insufficient in thevicinity of the nozzle center with respect to the yarn longitudinaldirection. Moreover, the supplied air pressure was 5 kg/cm² similarly.TABLE 1 Flame resistant Carbonizing Process Single process processpassing ratio yarn Filament Process Process Flame Bonding finenessnumber Time tension Time tension resistant Carbonizing part (dTex)(pieces) Connecting method (minutes) (mN/Tex) (minutes) (mN/Tex) processprocess Example 1 One-side 1.2 12000 After the entanglement and 30 14 27 100 100 flame connection, the end yarns were resistant cut with thescissors. process Example 2 One-side 1.2 24000 Same as above 60 14 2 7100 100 flame resistant process Example 3 One side 1.2 48000 Same asabove 60 14 2 7 100 100 flame resistant process Example 4 One-side 1.212000 After cutting the end yarns, the 30 14 2 7 100 100 flameentanglement and connection resistant were executed with the nozzleprocess moved. Example 5 Both-side 1.2 48000 After the entanglement and60 14 2 7 100 100 flame connection, the end yarns were resistant cutwith the scissors. process Com- One-side 1.2 12000 After theentanglement and 30 14 2 7  0 — parative flame connection, the end yarnswere example 1 resistant cut with the scissors. process

[0075] As it is apparent from the explanation above, at the time ofproducing a carbon fiber by supplying precursor fiber yarns to thefiring process including the flame resistant process and the carbonizingprocess, according to the present invention, in spite of the simplemechanism, the connecting device for obtaining a yarn having a highprocess passing property was developed. Accordingly, the completecontinuous production, which has not been realized by the conventionaltechnique, was enabled so that the operability of the firing process wasimproved remarkably and a low cost can be realized.

1. A production device for carbon fibers, for connecting precursor fiber yarns, being characterized in that the production device comprises a pair of yarn gripping devices for overlaying the precursor fiber yarns to be connected one upon another and gripping the overlaid yarns, and a fluid processing unit disposed between the pair of yarn gripping devices for applying an entangling process by jetting a plurality of rows of fluid with respect to a longitudinal direction of an overlaid part of the precursor fiber yarns, and a plurality of discontinuous thread handling areas of the precursor fiber yarns in a fluid jet area of the fluid processing unit are disposed at predetermined intervals in a longitudinal direction of the yarns.
 2. A production device according to claim 1, being characterized in that a cross-section of each thread handling area has a flat rectangular shape, and a plurality of fluid jet holes of the fluid processing unit are arranged at predetermined intervals in a longer side direction of the flat rectangular shape of the thread handling area.
 3. A production device according to claim 1 or 2, being characterized in that the fluid processing unit having fluid jet holes has a structure dividable into half in a longitudinal direction of overlaid yarns, and each of divided fluid processing units is integrated or mounted on a common base such that the thread handling areas arranged per row unit of the fluid jet holes have predetermined intervals.
 4. A production device according to claim 3, being characterized in that the fluid processing units divided into half are provided movably in a thread handling area direction independently.
 5. A production device according to claim 1, being characterized in that cutting means for the yarns is provided on both end sides of a thread handling area direction of the fluid processing unit and an inner side of the yarn gripping devices.
 6. A production device according to claim 1 or 2, being characterized in that a cutting position by cutting means is set within 30 mm from an end of a connecting portion overlaid and entangled.
 7. A production device according to any of claims 1 to 6, being characterized in that a temporary storage unit for temporarily storing precursor fiber yarns according to a tension fluctuation of the precursor fiber yarns being moved between a connecting device of the precursor fiber yarns for producing carbon fibers and a flame resistant process or a carbonizing process on a downstream side.
 8. A production method for carbon fibers, for continuously producing carbon fibers by connecting a trailing end of a preceding precursor fiber yarn and a leading end of a following precursor fiber yarn for the carbon fiber production with using a connecting device according to any of claims 1 to 7, being characterized by comprising the steps of: overlaying ends of precursor fiber yarns to be connected, gripping both ends of an overlaid part of the precursor fiber yarns by yarn gripping devices, and applying an entangling process to the overlaid part between the yarn gripping devices by jetting a plurality of rows of fluid with respect to a longitudinal direction of the overlaid part by a fluid processing unit.
 9. A production method for carbon fibers according to claim 8, being characterized in that at least one of the precursor fiber yarns to be connected is a flame resistant yarn or a flame resistant yarn provided by applying a flame resistant process to the connected ends.
 10. A production method for carbon fibers according to claim 8, being characterized in that each of the connected ends of the precursor fiber yarns to be connected is provided with a flame resistant process. 